Many different types of sensor devices exist for providing information about the tires of a wheeled vehicle. Features such as automatic stability and traction control in cars have made it necessary to obtain information about the interaction between the tires and the road surface. Such information is available from several sources, including ABS sensors, tire pressure measurement systems, and accelerometers and gyros located in the vehicle.
It is also desirable to obtain direct information about the tire-road interface. Known sensors for providing such direct information typically are mounted to the tire in various locations, such as in the tread, sidewall, inflation stem, etc. Existing sensor systems, however, tend to be complicated to operate and difficult to mount to the tire. Further, known tire sensor systems typically use only a single sensor attached to the tire lining or embedded in the tread. This limits the amount of data available for analysis. In particular, it is desirable to observe the tire deformation at both the sidewalls and in the tread, and to be able to observe short-term fluctuations (less than one wheel revolution) in the forces between tire and road.
Moreover, such sensors require an energy source to power the device—typically a battery. Eliminating the battery as the energy source for tire-mounted sensors is desirable from cost, reliability and environmental standpoints.
For these and other reasons, there is a need for the present invention.